8/18: National Guard heads to Ferguson as tensions remain high; Mapping the world's coral reefs like never before

August 18, 2014, 6:30 PM|Following yet another night of violence in which three people were shot, the governor of Missouri deployed the state's National Guard to Ferguson.; and, Jeff Glor tells us about a battle to save the world's coral reefs, waged by scientists and explorers armed with some very special cameras.